Brolin learned a lot about the film's 1940s setting from his father, actor James Brolin, and from stories he read about the real-life officers of the era.

"These guys were pretty brutal back then," he said recently, sitting outside City Hall, where he was shooting scenes for the Warner Bros. film, set to open Oct. 19. "I had this idea of how innocent it was back then, and then you hear that because there is no Internet, no iPhone, because there is none of that, you could get away with a lot of stuff, and they would."